I recently replaced the stock airbox with RPM Dual Pod's, and have the crankcase breather filter installed as a result of the stock airbox delete.
Is it normal to see quite a bit of vapor coming out of the breather, with the bike at operating temp and running? I was surprised to see this.
Quote from: aigram on November 01, 2018, 03:43:39 PM
I recently replaced the stock airbox with RPM Dual Pod's, and have the crankcase breather filter installed as a result of the stock airbox delete.
Is it normal to see quite a bit of vapor coming out of the breather, with the bike at operating temp and running? I was surprised to see this.
Normal... most stick the breather right up next to the pods so the gases are sucked into the intake. Some route a long hose to under the rear cowl which prevents most of the oil vapor smell.
Frank
I don't know if its normal but my 84 fj 1100 always has oil around the crankcase breather filter.It wouldn't be needed if the engine didn't naturally have a positive pressure so the vapor has to come out. I suppose the more blow by from worn rings the more vapor you might see ,but i still have good compression and it runs great s0 I just wipe up the oil every now and then and don't worry about it.
That vapor is normal. Stick the breather filter, under and in between #2 & #3 of the pod side of the carbs. The air box performs the same function for the crank case breather.
To be clear, I am a fan of the RPM Uni's and will never go back to the oem air box :good2:
.....However, there is a benefit the air box has that the Uni's do not, and that is: negative pressure.
This negative pressure in the air box actually pulls the blow by gasses by out of the crank case increasing the efficiency of the pistons on the down stroke.
(Too bad it also takes this dirty vapor and sends it back into the air filter and then thru the carbs)
Getting the crankcase under negative pressure adds free horsepower, something the Pro Stock drag bikes know all about. They run battery driven vacuum pumps to get their crank cases under high levels of negative pressure.
Quote from: Pat Conlon on November 01, 2018, 07:33:54 PM
To be clear, I am a fan of the RPM Uni's and will never go back to the oem air box :good2:
.....However, there is a benefit the air box has that the Uni's do not, and that is: negative pressure.
This negative pressure in the air box actually pulls the blow by gasses by out of the crank case increasing the efficiency of the pistons on the down stroke.
(Too bad it also takes this dirty vapor and sends it back into the air filter and then thru the carbs)
Getting the crankcase under negative pressure adds free horsepower, something the Pro Stock drag bikes know all about. They run battery driven vacuum pumps to get their crank cases under high levels of negative pressure.
Pat,
You're a big boy so it's okay to use the word VACUUM if you want. :-)
But, wouldn't you pay for that crankcase vacuum on the piston(s) upstroke? In theory, the pistons should displace a fixed volume with each other. The pistons going down would pump air under the pistons going up. I recall manufacturers working on "pumping efficiency" by using large holes between the cylinders below the piston travel to more easily move air between them.
Ideally a vacuum pump would only remove the excess blow by pressure and not create a vacuum in the crankcase that the rising pistons would have to fight against. I've always been amazed at the ingenuity of the people who seek fractions of a horsepower where ever they can find it. Smokey Yunick pops to mind.
maybe this is the solution
Hey David, oh hell yea, as a kid, I remember faithfully reading Smokey's columns in Popular Science. Smokey always said, with the IC engine, heat is always going to be present so why run away from it? Hence his adiabatic engine design. I really enjoyed his columns. He was quite a character. The "basketball trick" in his fuel tank was a classic. RIP Smokey.
Re: crankcase vacuum. I was at the NHRA Winternationals in Pomona, CA. several years ago hanging around the pits, talking with the gracious Pro Stock riders and their pit crews. I saw them start a bike, but before the put the starter motor on the crank, the bike started a loud buzzing, as in LOUD. They explained that that was the vacuum pumps running. Several small pumps to be exact, 2 or 3. The rules were rewritten 2 years ago to only allow 1 large pump. Here's some FAQ's: https://www.gzmotorsports.com/why-use-vacuum-pump.html (https://www.gzmotorsports.com/why-use-vacuum-pump.html)
Still, for wet sump engines 10"-15" vacuum is all that's recommended.
https://www.gzmotorsports.com/vacuum-pump-guide.html (https://www.gzmotorsports.com/vacuum-pump-guide.html)
As they explained, it's all about 1) ring seals and 2) the power stroke. Is seems that to reduce friction they run very low tension rings, thus get a lot of blow by the vacuum pumps address. I thought about vacuum and the upstroke of the piston but just the compression stroke would be affected and the exhaust stroke would have an open valve.
Anyhoo, buy a vacuum pump from Fast by Gast, put it on your FJ and he says it's good for 5 to 7 additional hp.
http://www.fastbygast.com/catagories/products/description/vacuum.htm (http://www.fastbygast.com/catagories/products/description/vacuum.htm)
....if you can put up with the noise.
Rick would love a vacuum pump on his FJ. That way when riding, he could remember his track days and following all those pesky Miatas...Bzzzzzzzzzzzz
Cheers
Quote from: Pat Conlon on November 02, 2018, 06:17:01 PM
...oh hell yea, as a kid, I remember faithfully reading Smokey's columns in Popular Science. Smokey always said......
I don't care what Smokey said, I think this woman understands 4 stroke engines pretty well.
(https://c1.staticflickr.com/5/4814/30755376217_43e3364cdb_c.jpg)
Noel
Quote from: Pat Conlon on November 02, 2018, 06:17:01 PM
Hey David, oh hell yea, as a kid, I remember faithfully reading Smokey's columns in Popular Science. Smokey always said, with the IC engine, heat is always going to be present so why run away from it? Hence his adiabatic engine design. I really enjoyed his columns. He was quite a character. The "basketball trick" in his fuel tank was a classic. RIP Smokey.
Pat, you remember the story about Smokey having his fuel tank removed in a NASCAR inspection and then he started the car and drove it back to his pits or how about the 7/8 scale Chevelle be built? He never saw a rule he couldn't bend. :biggrin:
Quote from: aigram on November 01, 2018, 03:43:39 PM
I recently replaced the stock airbox with RPM Dual Pod's, and have the crankcase breather filter installed as a result of the stock airbox delete.
Is it normal to see quite a bit of vapor coming out of the breather, with the bike at operating temp and running? I was surprised to see this.
I haven't taken the air box out yet. Does anyone know what size breather filter is required? Looks like 9mm or 12mm. Thanks
Here is what many here have installed.
http://rpmracingca.com/proddetail.asp?prod=Engine%3ABreatherFilter&cat=39 (http://rpmracingca.com/proddetail.asp?prod=Engine%3ABreatherFilter&cat=39)
(http://rpmracingca.com/prodimages/large/Engine%20BreatherFilter-1.jpg)
Quote from: Pat Conlon on November 02, 2018, 06:17:01 PM
Rick would love a vacuum pump on his FJ. That way when riding, he could remember his track days and following all those pesky Miatas...Bzzzzzzzzzzzz
Cheers
Fuckin' Miatas... :dash1:
Ha! (wondered when you would see that)
Good for you Rick...you took your time and gave that idea some serious thought before you responded. :good2: